Novel anti-staling enzyme, and methods, doughs and baked food products relating thereto

Abstract

The invention relates to the field of food technology and anti-staling enzymes. Provided is a method of preparing a baked food product by baking a farinaceous dough, comprising incorporating into the dough a GtfC-type 4,6-α-glucanotransferase enzyme, wherein the GtfC-type enzyme (i) is capable of transferring a maltose moiety from a polysaccharide or oligosaccharide substrate to the non-reducing end of an oligosaccharide acceptor via a new a(1->6) linkage without forming α(1->4,6) branching points, and (ii) has an activity optimum in the temperature range of 50-70° C. Also provided is a farinaceous dough and a baked dough product comprising said GtfC-t e 4,6-α-glucanotransferase enzyme.

What is claimed is: 
     
         1 . A method of preparing a baked food product by baking a farinaceous dough, comprising incorporating into the dough a GtfC-type 4,6-α-glucanotransferase enzyme, wherein the GtfC-type enzyme (i) is capable of transferring a maltose moiety from a polysaccharide or oligosaccharide substrate to the non-reducing end of an oligosaccharide acceptor via a new α(1->6) linkage without forming α(1->4,6) branching points, and (ii) has an activity optimum in the temperature range of 50-70° C. determined at pH 6 with amylose V as substrate. 
     
     
         2 . A farinaceous dough comprising a GtfC-type 4,6-α-glucanotransferase enzyme, wherein the GtfC-type enzyme (i) is capable of transferring a maltose moiety from a polysaccharide or oligosaccharide substrate to the non-reducing end of an oligosaccharide acceptor via a new α(1->6) linkage without forming α(1->4,6) branching points, and (ii) has an activity optimum in the temperature range of 50-70° C. determined at pH 6 with amylose V as substrate. 
     
     
         3 . The method or dough according to  claim 1 , wherein the GtfC-type enzyme has an activity optimum in the temperature range of 55-65° C. 
     
     
         4 . The method or dough according to  claim 1 , wherein the GtfC-type enzyme has at least 80% residual 4,6-α-glucanotransferase activity after incubating the enzyme in a 25 mM sodium citrate buffer containing 1 mM CaCl 2  at a temperature of 60° C. at pH 6 for 60 min. 
     
     
         5 . The method according to  claim 1 , wherein the GtfC-type enzyme has an activity optimum in the pH range of 4 to 7.5. 
     
     
         6 . The method according to  claim 1 , wherein the GtfC-type enzyme is incorporated in the dough in an amount of 100 to 20,000 U per kg of the total weight of starch in the dough. 
     
     
         7 . The method according to  claim 1 , wherein the GtfC-type enzyme is a polypeptide having the GenBank accession number AKM18207, or a functional fragment thereof having the desired GtfC-type 4,6-α-glucanotransferase activity. 
     
     
         8 . The method according to  claim 1 , wherein the GtfC-type enzyme is a polypeptide comprising an amino acid sequence having at least 80% identity to SEQ ID NO: 1 ( FIG.  1   ). 
     
     
         9 . The method or dough according to  claim 8 , wherein the polypeptide comprises the conserved motifs I, II, III and IV of the GTFC-like members of the GH70 family, wherein the motifs have the following amino acid sequences:
 Motif I: [M/E/L]DLVPNQ   Motif II: GFRIDAA[S/G/T]H[Y/F]D   Motif III: HLSYIESY[K/S/Q/T][S/N][E/V/A/K]   Motif IV: FV[N/T]NHDQEKNR[V/I]N[Q/N/T].   
     
     
         10 . The method according to  claim 1 , wherein the dough is prepared by combining flour, water, yeast, GtfC-type 4,6-α-glucanotransferase enzyme and optionally other bakery ingredients. 
     
     
         11 . The method according to  claim 1 , wherein the dough is a wheat flour dough. 
     
     
         12 . The method according to  claim 1 , wherein the dough is a gluten-free or gluten-reduced dough. 
     
     
         13 . A baked food product obtainable by a method according to the method of  claim 1 . 
     
     
         14 . A baked food product obtained by baking a farinaceous dough comprising a linear α-glucan comprising alternating (α1→6)/(α1→4) glycosidic bonds and having no (α1→4,6) branching points, less than 0.5% consecutive (α1→6) glycosidic bonds and less than 0.5% consecutive (α1→4) glycosidic bonds. 
     
     
         15 . A method to increase the shelf-life of a baked food product, comprising incorporating into a farinaceous bread dough a GtfC-type 4,6-α-glucanotransferase enzyme which is capable of transferring a maltose moiety from a polysaccharide or oligosaccharide substrate to the non-reducing end of an oligosaccharide acceptor via a new α(1->6) linkage without forming α(1->4,6) branching points, and wherein the GtfC-type enzyme has an optimum temperature in the range of 50-70° C. determined at pH 6 with amylose V as substrate, and baking the dough. 
     
     
         16 . (canceled) 
     
     
         17 . (canceled)